Corneal Microcysts Common in Children Wearing Ortho-K Lenses During COVID-19 Lockdowns

Orthokeratology lens wearers run the risk of developing corneal microcysts if they sleep in their lenses longer than 10 hours.

Corneal microcysts were frequently observed in children wearing orthokeratology (ortho-k) lenses for myopia control during the COVID-19 lockdowns in Hong Kong, “probably due to lifestyle changes,” according to research published in Contact Lens and Anterior Eye. Higher myopia may be associated with a higher prevalence of corneal microcysts, the report suggests. 

This retrospective cross-sectional study included 95 children with myopia using ortho-k lenses who were examined by 1 of 3 independent investigators between March 2020 and September 2020.

All children included in the study were existing ortho-k wearers who had been treated for 4 months to 4 years. Study participants were instructed to wear their lenses every night and return for regular follow-up visits.

For children with corneal microcysts, the researchers retrieved and analyzed data from the baseline visit and the first visit at which the microcysts were observed. For children with no microcystic response, the researchers retrieved data from the baseline visit and the final visit within the study period.

The use of highly oxygen permeable lenses and frequent aftercare are necessary for ortho-k wearers, especially those with higher myopia.

Corneal microcysts were observed in 52.6% of children wearing ortho-k lenses. Overall, 100% (23/23) of participants with high myopia and 37.5% (27/72) of participants with low myopia were observed with corneal microcysts.

Before the COVID-19 lockdowns, the researchers explain that patients with high myopia slept an average of 8.3±0.8 hours a night, but that during the lockdowns they slept 10.2±1.4 hours (Independent t test, P <.001), with nearly 3 quarters of patients sleeping more than 10 hours. However, no significant differences in sleep duration were noted between participants with low myopia.

Researchers suggest this lifestyle change could have increased the risk of corneal microcysts and suggest issuing reminders to not sleep with lenses longer than 10 hours.

Microcysts were mainly (86.0%) observed in the region of the inferior pigmented arc, typically originating in the inferior mid-peripheral cornea, and expanding over time into a semi- or whole annulus, the report notes. 

The univariate analyses showed that participants with low myopia with greater baseline myopia or topographic change at the treatment zone center tended to have a higher incidence of microcysts. 

In participants with low myopia, microcysts were more frequently observed in girls (48.8%) than boys (18.5%).

“Practitioners should examine ortho-k wearers with caution using a slit lamp with high magnification and illumination, especially the mid-peripheral cornea,” according to the study. “The use of highly oxygen permeable lenses and frequent aftercare are necessary for ortho-k wearers, especially those with higher myopia.”

Study limitations include the lack of recording of corneal microcysts before starting ortho-k treatment and the different sample sizes of the groups. 


Yang Y, Vincent SJ, Cheung SW, Guo B, Cho P, Efron N. Characteristics of corneal microcysts in Hong Kong children wearing orthokeratology. Cont Lens Anterior Eye. Published online August 23, 2023. doi:10.1016/j.clae.2023.102047